After remaining primarily in the pocket for most of the season, 49ers quarterback Colin Kaepernick returned to his dual-threat ways to lead San Francisco to its fourth straight win, a 31-17 victory over the Titans on Sunday.

In the first half, Kaepernick had a 20-yard touchdown run on a read-option play and 50 of his 68 rushing yards as the Niners took a 17-0 halftime lead and were never seriously challenged.

Why did the 49ers dust off the read option? Jim Harbaugh and several offensive players said film study suggested the Titans could be exploited by those package of plays.

“It was definitely something that’s been in the game plan all year,” left tackle Joe Staley said. “We just hadn’t run it as much as we had in the past. We just saw something that they were giving us during the week in preparation that we could advantage of. And we were able to.”

After tormenting defenses with his legs last year, Kaepernick entered Sunday with fewer than 23 rushing yards in five of six games this season and hadn’t scored a touchdown since the fourth quarter of Super Bowl XLVII. In fact, his 50 first-half rushing yards Sunday topped his combined total (43) in his previous three games.

Four days before kickoff, Titans coach Mike Munchak applauded what he viewed as San Francisco’s cautious approach with its franchise quarterback, saying the “less he runs probably the better” to avoid injury.

Instead, Kaepernick ran more and it made matter worse for the Titans.

With the 49ers leading 3-0 in the second quarter, Kaepernick faked a read-option handoff to running back Frank Gore on 3rd-and-7, kept the ball and sprinted around left end for a 20-yard touchdown and first biceps-kiss celebration of the season.

On San Francisco’s next possession, Kaepernick’s wheels again extricated the 49ers from an unenviable situation.

On 3rd-and-11 from Tennessee’s 46-yard line, he escaped pressure for a 20-yard gain, getting an assist from wide receiver Anquan Bolin’s de-cleating block on cornerback Alterraun Verner. Three plays later, Gore had the first of his two one-yard touchdown runs.

Kaepernick absorbed several big hits – in and out of the pocket – and Harbaugh acknowledged the need to protect him from such collisions, before smiling: “You have to catch him first, though.”

Kaepernick, who completed 13 of 21 passes for 199 yards, headlined what was arguably San Francisco’s most complete win of the season.

Linebacker Patrick Willis (team-high nine tackles), defensive tackle Justin Smith (2 sacks) and cornerback Tramaine Brock (interception) led a defense that limited the Titans to eight first downs and zero points in the first three quarters, allowing the 49ers to grab a 24-0 lead.

Meanwhile, the special teams provided their final points when Kassim Osgood receovered a muffed punt in the end zone to give the 49ers a 31-10 lead with 6:16 left. Punter Andy Lee dropped three punts inside Tennessee’s 20-yard line and the Titans (3-4) started their average drive at their own 21.

Smith doesn’t rate wins, but he said a convincing victory away from home was satisfying.

“On the road, in the NFL, it’s big,” Smith said. “It’s hard to win in other people’s stadiums and we felt like they were a pretty good football team. I’m excited about it. I don’t know about anyone else.”

There’s plenty for the 49ers to be excited about after steamrolling their past four opponents, 132-51, and scoring 30 points in four straight contests for the first time since 1998. San Francisco has also posted four consecutive double-digits wins for the first time since 1997.

Looking ahead, Gore noted more reasons for optimism. Mario Manningham and Michael Crabtree could both be back by mid-November to help remedy the 49ers’ lack of a reliable No. 2 wide receiver.

On Sunday, Boldin (5 catches, 76 yards), who had three highlight-reel grabs, was the only wideout with a reception. In addition, Harbaugh said after the game that All-Pro outside linebacker Aldon Smith could rejoin the team in the “next couple weeks.” Smith is in a treatment facility for a reported substance-abuse problem and has missed the past four games.

“We’re coming,” Gore said. “We’ve got a lot of keys guys out, but this team is special. … When we have Mario, Crab, (other guys) come back who haven’t been playing, it’s going to be crazy.”